On Thu, 28 Feb 2019, Dongli Zhang wrote: > > The root cause is that the return type of jiffies_to_usecs() is 'unsigned int', > but not 'unsigned long'. As a result, the leading 32 bits are discarded. Errm. No. The root cause is that jiffies_to_usecs() is used for that in the first place. The function has been that way forever and all usage sites (except a broken dev_debug print in infiniband) feed delta values. Yes, it could have documentation.... > jiffies_to_usecs() is indirectly triggered by cputime_to_nsecs() at line 264. > If guest is already up for long time, the initial steal time for new vcpu might > be large and the leading 32 bits of jiffies_to_usecs() would be discarded. > So far, I have two solutions: > > 1. Change the return type from 'unsigned int' to 'unsigned long' as in above > link and I am afraid it would bring side effect. The return type in latest > mainline kernel is still 'unsigned int'. Changing it to unsigned long would just solve the issue for 64bit. Thanks, tglx
